It is well known that following human heart transplantation there is danger of rejection of the new heart by the host patient. Such rejection, referred to as cardiac allograft rejection, has been widely studied and discussed in the medical literature. While techniques dealing with, i.e. treating such rejection, have advanced greatly, there still remains a need for accurate, noninvasive, safe and relatively simple diagnosis of such rejection.
One technique for determining the condition of the transplanted heart is to perform a biopsy. However, such an invasive technique is clearly not desirable, and there is a substantial need for an accurate and reliable noninvasive means of diagnosis.
The depolarization phase (QRS) of the surface electrocardiogram has been determined to be a sensitive indicator of myocardial damage, but has proved disappointing in the diagnosis of cardiac allograft rejection. The prior art has employed an implanted lead and an implanted pacemaker in an attempt to predict rejection based upon the amplitude of the depolarization (QRS) wave, but concluded that depolarization wave amplitude is not a reliable indicator of rejection. In this prior scheme, the depolarization wave data was transmitted by telemetry from the pacemaker to an external programmer/transceiver in real time, and then recorded with an EKG recorder.
The inventor of the instant application has discovered that amplitude of the repolarization wave (T-wave), as well as other characteristics of the heartbeat signal, including characteristics of the QRS and T-waves, can, in fact, be employed to predict rejection, as well as to indicate the need for drug treatment or other therapy not necessarily related to heart transplantation. It is believed by the inventor that, in the prior art attempt described above, either degradation of the depolarization wave data during transmission by the pacemaker (as a result of the real time transmission of raw data), or pacemaker inadequacies such as lack of sensitivity, or both, resulted in failure to appreciate the phenomena and hence an erroneous conclusion.
The present invention addresses the acute need for an improved noninvasive technique for both diagnosing rejection of a transplanted heart in a human patient, as well as indicating the need for drug treatment or other therapy not necessarily related to heart transplantation.